U.S. patent number 5,744,962 [Application Number 08/404,031] was granted by the patent office on 1998-04-28 for automated data storing battery tester and multimeter.
Invention is credited to Glenn Alber, Edward W. Deveau.
United States Patent |
5,744,962 |
Alber , et al. |
April 28, 1998 |
Automated data storing battery tester and multimeter
Abstract
An intelligent automated battery multimeter system having data
storing and multi-cell reading capabilities in a self-contained
unit for automatically performing in-service DC load testing on
battery cells without requiring the removal of battery chargers
wherein the tester measures, records and displays load voltages,
float voltages, internal cell resistance, intercell connection
resistance and other cell integrity measurements. The battery
tester is also computer compatible wherein it provides PC links for
extracting data from the system and downloading it into computer
networks.
Inventors: |
Alber; Glenn (Boca Raton,
FL), Deveau; Edward W. (Boca Raton, FL) |
Family
ID: |
23597855 |
Appl.
No.: |
08/404,031 |
Filed: |
March 14, 1995 |
Current U.S.
Class: |
324/426; 324/433;
324/430 |
Current CPC
Class: |
G01R
31/3648 (20130101); G01R 31/385 (20190101); G01R
31/386 (20190101) |
Current International
Class: |
G01R
31/36 (20060101); G01R 027/26 () |
Field of
Search: |
;324/427,433,429,430
;340/636,48 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Regan; Maura K.
Attorney, Agent or Firm: Malin, Haley, DiMaggio &
Crosby, PA
Claims
What is claimed is:
1. A data storing battery tester and multimeter for testing at
least one battery in a plurality of batteries to predict whether
said battery can provide a predetermined power level by determining
at least the battery internal cell resistance, said battery being
electrically connected in series by at least one conductive
intercell link, said battery and batteries being connected to and
used to supply power in electrical systems, said tester
comprising:
an adjustable direct current (DC) resistance load;
resistance loading means, in electrical communication with said
adjustable load, for selectively and automatically applying and
removing said adjustable load across said battery while said
battery remains connected to the electrical system to facilitate a
load voltage and a float voltage, respectively, and to draw
current;
processor means, in electrical communication with said resistance
loading means, for reading said load voltage, said float voltage
and said current draw and for calculating resistance of the
intercell link and said internal cell resistance using said
voltages and said current draw; wherein said load voltage, float
voltage, current draw, intercell link resistance and internal cell
resistance comprise data, said processor means including a
prediction means for determining whether the battery can provide
the predetermined power level based on said data;
memory means, in electrical communication with said processor
means, for storing an algorithm used by said processor means to
read and calculate said data and for storing said data
computer interface means, in electrical communication with said
processor means, for communicating and interfacing with at least
one computer peripheral to facilitate transferring said data to
said computer; and
signal control means, in electrical communication with said
resistance loading means and said processor means, for receiving
input command signals and electrically providing output control
signals to said processor means to facilitate the applying and
removing of said adjustable load from said battery and processing
of said data.
2. A battery tester as recited in claim 1, wherein said processor
means comprises a microprocessor.
3. A battery tester as recited in claim 2, wherein said tester
further comprises:
signal transfer means, in electrical communication with said
processor means, memory means and resistance loading means, for
electrically interfacing said processor means, memory means and
resistance loading means for allowing said data to be transferred
in multiple bytes.
4. A battery tester as recited in claim 3, wherein said resistance
loading means further comprises means for amplifying signals
generated by said battery to facilitate processing of said load and
float voltages.
5. A battery tester as recited in claim 4, further comprising user
interface means, in communication with said processor, for allowing
a user to select and control said resistance loading means to
control the applying and removing of said adjustable load.
6. A battery tester as recited in claim 2, wherein said resistance
loading means comprises:
a load module driver in electrical communication with said
adjustable load; and
a plurality of electrically controlled switches electrically
controlled by said load module driver for applying and removing
said adjustable load.
7. A battery tester as recited in claim 1, wherein said tester
further comprises:
multiplexor means, in electrical communication with said processor
means and said resistance loading means, for receiving analog
signals indicating said load and float voltage and said current
draw and for directing said signals to said processor means in a
predetermined order to predetermined locations in said processor
means.
8. A battery tester for predicting whether a battery in a plurality
of batteries will be able to provide required power to a known load
based on at least internal cell resistance in said battery and
intercell resistance of a conductive link electrically joining said
battery to said plurality of batteries, said battery and batteries
being connected to used to supply power to an electrical system,
said tester comprising:
an adjustable direct current (DC) resistance load;
resistance loading means, in electrical communication with said
adjustable load, for selectively and automatically applying and
removing said adjustable load across said battery while said
battery remains connected to the electrical system to facilitate a
load voltage and a float voltage, respectively and to a current
draw;
a programmable processor means, in electrical communication with
said resistance loading means, for reading said load and float
voltages and said current draw and for calculating said internal
cell resistance and intercell resistance using said voltages and
said current draw, wherein said load voltage, float voltage,
current draw, intercell resistance and internal cell resistance
comprise data, said processor means including a prediction means
for determining whether the battery can provide the predetermined
power level based on said data;
memory means, in electrical communication with said processor
means, for storing an algorithm used by said processor means to
read and calculate said data and for storing said data;
parallel input-output (I/O) controller, in electrical communication
with said resistance loading means and said processor means, for
receiving input command signals and electrically providing output
control signals to said processor means to facilitate the applying
and removing of said adjustable load from said battery and
processing of said data; and
user interface means, in electrical communication with said
parallel I/O controller and said processor, for initiating said
processor means and said resistance loading means to control the
applying and removing of said adjustable load and to determine
whether said battery can provide said required power.
9. A battery tester as recited in claim 8, wherein said tester
further comprises:
an analog-to-digital converter, in electrical communication with
said signal control means and said processor means; and
multiplexor means, in electrical communication with said processor
means, said analog-to-digital converter and said resistance loading
means, for receiving analog signals indicating said load and float
voltage and said current draw, for sending selected signals from
said analog signals to said analog-to-digital converter to convert
to digital signals, and for directing said analog signals to said
processor means in a predetermined order to predetermined locations
in said processor means.
10. A battery tester as recited in claim 9, wherein said tester
further comprises:
computer interface means, in electrical communication with said
processor means, for communicating and interfacing with at least
one computer peripheral to facilitate transfering said data to said
computer.
11. A battery tester as recited in claim 10, wherein said tester
further comprises:
amplifier means, in electrical communication with said resistance
loading means, for amplifying signals comprising said load and
float voltages to facilitate processing; and
voltage divider means, in electrical communication with said
multiplexor means, for reducing voltage levels in signals
comprising said load and float voltages.
12. A battery tester for predicting whether a battery in a
plurality of batteries will be able to provide required power to a
known load based on at least internal cell resistance in said
battery and intercell resistance of a conductive link electrically
joining said battery to said plurality of batteries, said battery
and batteries being connected to used to supply power to an
electrical system, said tester comprising:
an adjustable direct current (DC) resistance load;
resistance loading means, in electrical communication with said
adjustable load, for selectively and automatically applying and
removing said adjustable load across said battery while said
battery remains connected to the electrical system to facilitate a
load voltage and a float voltage, respectively and to a current
draw;
a programmable processor means, in electrical communication with
said resistance loading means, for reading said load and float
voltages and said current draw and for calculating said internal
cell resistance and intercell resistance using said voltages and
said current draw, wherein said load voltage, float voltage,
current draw, intercell resistance and internal cell resistance
comprise data, said processor means including a prediction means
for determining whether the battery can provide the predetermined
power level based on said data;
memory means, in electrical communication with said processor
means, for storing an algorithm used by said processor means to
read and calculate said data and for storing said data;
parallel input-output (I/O) controller, in electrical communication
with said resistance loading means and said processor means, for
receiving input command signals and electrically providing output
control signals to said processor means to facilitate the applying
and removing of said adjustable load from said battery and
processing of said data;
computer interface means, in electrical communication with said
processor means, for communicating and interfacing with at least
one computer peripheral to facilitate transferring said data to
said computer; and
user interface means, in electrical communication with said
parallel I/O controller and said processor, for initiating said
processor means and said resistance loading means to control the
applying and removing of said adjustable load and to determine
whether said battery can provide said required power.
13. A battery tester as recited in claim 12, wherein said tester
further comprises:
an analog-to-digital converter, in electrical communication with
said signal control means and said processor means; and
multiplexor means, in electrical communication with said processor
means, said analog-to-digital converter and said resistance loading
means, for receiving analog signals indicating said load and float
voltage and said current draw, for sending selected signals from
said analog signals to said analog-to-digital converter to convert
to digital signals, and for directing said analog signals to said
processor means in a predetermined order to predetermined locations
in said processor means.
14. A battery tester as recited in claim 13, wherein said
resistance loading means comprises:
a load module driver in electrical communication with said
adjustable load; and
a plurality of electrically controlled switches in electrically
controlled by said load module driver.
15. A battery tester as recited in claim 14, wherein said tester
further comprises:
amplifier means, in electrical communication with said resistance
loading means, for amplifying signals comprising said load and
float voltages to facilitate processing; and
voltage divider means, in electrical communication with said
multiplexor means, for reducing voltage levels in signals
comprising said load and float voltages.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to battery test equipment
for monitoring self integrity, and more particularly, to an
intelligent automated battery multimeter system having data storing
and multi-cell reading capabilities in a self-contained unit for
measuring, recording and displaying self float voltages, internal
cell resistance, intercell connection resistance and other cell
integrity measurements. The present invention also provides a
computer interface to download data to a computer for extracting
data from the system and downloading it into computer networks.
2. Description of the Background Art
The internal resistance of battery cells dictates and indicates the
capacity of a battery to supply power to a known load or circuit.
The internal resistance of each cell in a battery source should be
monitored and measured periodically to insure that a battery is
maintaining full capacity. Taking measurements of this cell
resistance is especially important for utility companies, phone
companies, hospitals, stock exchanges, credit card companies,
businesses having 24 hour on-line computer services and any company
that relies on battery backup power as a source of uninterrupted
power supply. Based on field testing of various types of batteries,
such as lead, lead acid and lead calcium batteries, once a battery
cell's internal resistance increases to more than 25% above its
nominal value, the cell and battery are unable to meet their
capacity requirements and fail capacity tests. The electrical
resistance of storage battery cells is also an important
measurement in telephone systems that use a central station
battery. Cell resistance can help in ascertaining potential cross
talk in telephone equipment and evaluating the amount of filtering
required to remove hum, voice, and switching pulses from the output
of battery charging equipment.
A simplified circuit model a load cell battery is shown in FIG. 1,
which comprises natural capacitance X.sub.C, electromechanical
resistance R.sub.E, and metallic resistance R.sub.M. The
electromechanical resistance is the cell's internal resistance and
equals the sum of the resistance due to cell paste used on the
cell's metallic grids, electrolytes in the cell and separators. The
natural metallic resistance comprises resistance due to the battery
terminal posts, strap, grids and grid to paste. As the
electromechanical resistance is much lower than the metallic
resistance, it is difficult to isolate and measure the
electromechanical resistance for predicting battery cell capacity
failure. Moreover, cell resistance measurements are frequency
dependent when using conventional equipment because of the
capacitance X.sub.C present across the electromechanical resistance
R.sub.E.
Conventional techniques and equipment for predicting battery
failure and measuring battery capacity require the removal of the
battery from service or from its battery charger. The battery is
removed from service to avoid noise problems, allow the placement
of a purely resistive load across the battery, and eliminate the
presence of reactance in measurements. Probably the most common
test used today for locating failing battery cells is the impedance
test. The impedance test employs an AC current injection method
wherein a known alternating current is injected into the unknown
impedance and the resulting voltage observed. This presents several
problems. For instance, the impedance test, as the name suggests,
provides impedance measurement rather than true resistance
measurements.
Due to the presence of capacitance in a battery cell, impedance
values are obtained when injecting current into the battery. Thus,
resistance readings are directly affected by the frequency of the
input current injected into the cell. Since impedance is a two
dimensional measurement of reactance and resistance, accurate
resistance measurements are not possible by the impedance test.
Impedance measurements are affected by the frequency of the
injected current such that resistance measurements can be 3 to 5
percent off. In fact, the larger the frequency of the AC current
injected, the larger the reactance and the less accurate the
resistance measurement. For example, at 45 Hz, resistance
measurements are known to be 80% the value of the resistance
measured at 5 Hz. A particularly bad choice of test current
frequency is 60 Hz in the United States and 50 Hz in the majority
of the world, that being the frequency of normal outlet power. Due
to the internal capacitance of a battery cell, low frequency
current, e.g. 5 Hz, must be injected to reduce the likelihood of
inaccurate resistance measurements affecting the overall cell
integrity analysis. The lower the frequency the better the results
wherein a DC input provides the most accurate resistance
measurements. The problem is that most equipment used utilizes the
60 Hz power provided through all outlets and requires the battery
or batteries be disconnected to perform true DC resistive loading
testing as no batter testers known can perform DC resistance
testing while the battery is in service.
Another problem with the impedance test is that inaccurate
measurements are obtained because of the presence of noise in the
battery charger and underlying circuit. Like other equipment,
battery chargers used are operated with conventional AC or 60 Hz
outlet power which creates noise affecting impedance measurements.
Since cells must be tested under normal conditions, and while in
service for meaningful measurements to be made, the battery charger
remains connected during testing. This is undesirable because AC
alternating current injection methods are susceptible to battery
charger ripple currents and other noise sources especially with
outlet power supplied at 60 Hz. In addition, some instruments
cannot be used while the battery is in service and/or connected to
the battery charger and load in normal full float operation. These
frequencies, however, are often the only source of alternating
current available and provide the primary charge ripple and noise
source frequency. By way of example, it is not uncommon to have RMS
ripple current in excess of 30 amps flowing through large
uninterrupted power supply batteries. Moreover, it is simply
undesirable to remove a backup battery from service to take
electrical cell resistance measurements when that battery source is
providing the insurance necessary in the event of main power
failure.
Another measurement device employed for determining battery cell
integrity is the conductance meter. This instrument is primarily
used by the automotive market and performs essentially the same
type of measurements as the impedance test equipment. The only
difference between the impedance test and the conductance test is
that the value displayed by the instrument is conductance rather
than impedance wherein the two are inversely related. Consequently,
the same problems are associated with the conductance meter as
noted above as they both inject AC current through the battery
under test.
The oldest test conducted under battery cells is the load test.
This type of test simulates the load being powered and injects AC
current through the battery under test. With this test the battery
is still subject to noise from the battery charger, and is
frequency sensitive. There are also DC loading tests which manually
place a load across a battery. These tests, however, are
incomplete, slow and must be manually performed. During a DC load
test, the battery experiences an instantaneous voltage drop and
then a recovery in voltage when the load is removed or floating.
Therefore, to obtain an accurate measurement of the battery cell
capacity, measurements for both loaded conditions and floating
loads must be made and time must be allotted for battery voltage
recovery. These drops in battery voltage are due to internal
resistance and are often enough to make a difference in meaningful
battery capacity predictions. Moreover, since battery modules often
include many batteries connected in series by external intercell
connectors, resistance measurements for predicting breaks are
equally important but nonetheless neglected.
In accordance with the foregoing, instruments presently available
use either AC current injection methods or momentary manual load
tests. AC injection instruments, such as impedance or conductance
meters, apply test signals through the battery and measure the
resulting AC voltage. These readings vary with the frequency of the
injected current and the value of capacitive reactance in the
battery which in turn lowers the electrochemical resistance
determinations made and their corresponding accuracy. Meanwhile the
DC load test instruments available for measuring internal battery
resistance in the cells do not account for normal cell voltage
drops which occur in a battery when a load is applied across its
terminals. The instantaneous drop when a load is applied, or the
instantaneous voltage recovery when the load is removed, is due to
the internal resistance. Currently, there are no DC load testing
instruments which account for the instantaneous voltage drop and
which can perform the instantaneous high speed calculations
necessary for obtaining accurate resistance readings. This is
because prior to the present invention there have been no battery
testing equipment having analog to digital (A/D) converters or
microcontrollers able to process the information, account for load
applied voltage drops in the battery and make integrity
measurements based on load and float voltages.
Consequently, the most reliable way to test a battery's capacity
and ability to perform is to perform DC load test across the entire
string of a battery module. Such a testing technique, however, has
proven to be time consuming and inconvenient in the past because it
requires a series of manual connections, measurements, recordation
and calculations. Moreover, to accurately measure battery
resistance and perform DC load testing, conventional techniques
require the battery be disconnected from service and the charger
removed. This, of course, compromises other important measurements
as discussed herein. Therefore, DC load testing would be well
received if automated test equipment was available which could
automatically measure, calculate and log voltage, current and
resistance data from individual cells subjected to load currents
that match the normal operating load while the battery or batteries
remain in service and are being charged. Such a load test could
perform a 100% integrity check and identify existing problems with
either the internal cells or the external intercell resistance
paths without compromising backup battery power. Prior to the
present invention, automated battery testing equipment as described
has not been available. Therefore, automated test equipment capable
of providing complete integrity checks on a battery cell
performance criteria would be well received. Accordingly, the
instant invention provides automated battery test equipment for
storing data, performing calculations and ascertaining the
integrity of battery cells automatically and which is also capable
of downloading battery test data into computers for further case
analysis.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an automated
battery tester for determining battery cell integrity for one or
more cells using DC load measurements.
It is also an object of the present invention to predict whether a
battery source will be able to provide required power to a known
load.
It is an additional object of the present invention to provide an
automated battery tester for predicting battery performance based
on internal cell resistance measurements and which may also perform
as a multimeter.
It is a further object of the instant invention to provide an
automated battery tester for determining battery capacity based on
internal cell resistance measurements obtained by load testing the
battery source and performing calculations from voltage and current
measurements.
It is still an additional object of the instant invention to
provide an automated battery tester for performing automatic load
testing on battery cells, making internal cell resistance
measurements, storing internal cell resistance measurements, and
performing calculations for determining the battery voltage
capacity with and without loading. It is still another object of
the instant invention to provide an automatic battery tester which
performs a DC load test to calculate internal cell resistance and
intercell resistance.
It is still a further object of the instant invention to provide an
automated battery tester which automatically stores data up to 8
strings and 260 cells each being performed in a time efficient
manner and which guarantees a permanent record of readings.
It is yet another object of the instant invention to provide an
automated battery tester which internally performs data analysis
and displays internal cell resistance measurements, intercell
resistance, temperature readings, specific gravity readings,
voltage readings from the battery, underload, float voltage and
overall battery capacity on an easy to read display.
It is yet an additional object of the instant invention to provide
an automated battery tester which provides a display window design
for easy reading of displayed instructions and results.
It is yet a further object of the instant invention to provide an
automated data storage battery tester which provides substantially
100% battery cell integrity measurements while a battery is in
service and fully connected to its battery charger.
It remains an object of the instant invention to provide an
automated battery tester having serial port interface capabilities
and computer interface compatibility for downloading storage data,
menu options, instructions and/or other test information for
further battery analysis.
In light of these and other objects the instant invention comprises
an automated data storage battery tester and multimeter system for
performing DC load testing on at least one battery cell or a
plurality of battery cells (battery source module), while the
battery or battery source is in service and being charged by its
battery charger.
The foregoing objects are accomplished by the present invention
which automatically performs DC load testing and internal cell
resistance measurements while the battery remains in service and
charged. A cell's internal resistance has proven to be a very
reliable indicator of the state of health and capacity of a battery
and it offers a cost effective solution to manual DC load testing
and more reliable results than AC current injecting methods as
conducted in the past.
The internal resistance of a cell is closely related to its
capacity and therefore it can be used to predict the cell's
performance during a discharge. A discharge is nothing more than
the drawing of current and power from the battery. Therefore, the
battery tester of the present invention performs DC load testing by
automatically placing selected loads across the battery to draw a
DC current and take voltage drop current draw measurements with and
without the load in a predetermined timed sequence. The voltage and
current measurements are used for arriving at internal cell and
intercell resistance calculations. The battery tester disclosed
performs the load and float voltage measurements with the battery
and battery charger in service for resistance determinations
without the side effects of noise, AC ripple, voltage drop and
impedance.
Batteries must be periodically tested for cell integrity. As a
battery loses capacity the internal resistance slowly increases
over time. Once internal electromechanical cell resistance exceeds
25% of its nominal value cells are known to fail capacity tests.
Even though there is a close correlation between a battery cell's
internal resistance and its capacity, it is not completely linear.
Therefore, the instant invention does not use the internal cell
resistance measurements therefore are not used as a direct
indicator of capacity, but rather as a warning indicator that
signals whether a cell has deteriorated to a level that will affect
the operating integrity of the battery. The instant invention also
performs other tests to completely analyze and ascertain the health
and integrity of the battery to predict its future performance. For
instance, the battery tester measures intercell connector
resistance to insure battery source or module integrity by checking
for intermittent connections between series connected cells, or
otherwise, for determining full power source capacity and for
dangerous loose connections.
The battery tester of the instant invention measures internal cell
resistance, intercell resistance, float voltages and load voltages,
and records a cell's specific gravity and cell temperature from
manual computer inputs. The instant invention stores data readings
in a data storage RAM and also provides a scratch pad memory RAM
for temporary storing of measurements used in performing
calculations. The battery tester includes microprocessor readable
algorithms for operating the hardware and making calculations. The
software algorithm is stored in program ROM and updated software is
stored in update ROM. The ROMs and RAMs are controlled by a
microcontroller, or a microprocessor. A multiplexer (MUX) receives
and sends voltage and current signal inputs to perform information
switching and routing for software controls and commands and
hardware manipulation. Switches, such as relays, solenoid relays or
solid state relays, are used by the tester for applying loads,
input dividing, and routing signals to RAMs, ROMs and the
displays.
The instant invention measures load voltage, float voltage and
current draw nd processes this data to compute internal cell
resistance. The battery tester first places a predetermined and
selected load across the battery drawing a measured DC current from
the cell through that load. The load is selected by manipulating a
corresponding switch, or keypad entry, which triggers a
corresponding relay dropping the load across the required terminals
automatically. By injecting DC current rather than AC current the
noise and ripple side effects from the charger are not realized and
a true load test may be accomplished while the battery remains in
service. Load voltage and DC current draw are measured and recorded
when injecting the DC current from the battery through the load. To
measure float voltage, the load is removed, a short predetermined
amount of time is allowed to pass, e.g. 30-40 m sec., and a float
voltage reading is recorded. Thus, the no load voltage reading is
recorded after removing the load. To arrive at the internal cell
resistance, the battery tester software subtracts the float voltage
reading from the load voltage reading and divides the difference by
the current draw measured. The instant invention also provides for
battery voltage drop through timed measurements. The no load
voltage reading is referred to as the float voltage, which is the
battery voltage while the battery is charged without a load applied
and this informs the user whether the charger is set or sitting at
the right voltage when not in use. Reading a float voltage also
helps determine whether a cell is suffering from a short, which
would be indicated by a low float voltage measurement.
Additionally, intercell resistance is measured and calculated by
measuring the voltage drop across the intercell connect and
dividing it by its current draw. All measurements and calculations,
i.e. float voltage, load voltage, current intercell resistance, and
internal cell resistance are stored in data RAM. Numbers used in
calculating are also temporarily stored in scratch pad memory
RAM.
In the preferred embodiment of the instant invention, the data
storage battery multimeter may be used on a single cell or a
multi-cell module. Readings up to 8 strings at 250-260 cells each
can be stored in the battery tester multimeter in a RAM location
having preferably two megabyte capacity. These numbers are merely
examples and are not intended to limit the scope and spirit of the
invention.
The preferred embodiment of the instant invention provides a self
contained, battery powered unit preferably comprised of a
microprocessor or microcontroller, adjustable selectable load
resistance, a display and a rechargeable battery. The instant
invention may be powered by AC wall adapters and also provides
backup battery power. The microcontroller may be defined as a
microprocessor including the RAM and ROM memory capacities for data
and program storing, respectively. The instant invention may
include two sets of test leads where the first set is a standard
set of digital voltmeter probes for voltage reading and the other
set is a pre-clip set used in the multimeter mode for other
measurements. The second set is used for making internal cell and
intercell resistance readings. To obtain an internal cell
resistance integrity measurement, the second set comprises two dual
connected test clips which are connected across the cell and its
associated intercell connector, that is from the positive post of
the cell being tested to the positive post of the next cell. The
dual conducting clips provide two different conductive paths are
provided, one for applying a load through the clips and the other
for taking measurements. The intercell connector is a conductor
link used to connect the negative terminal from one battery (such
as the cell being tested) to the positive terminal of another (such
as the next cell) to connect the batteries in series for increased
battery voltage or power capacity. Thus, the two dual conductor
test clips are connected from the positive post of one cell being
tested to the positive post of the adjacent series connected cell.
A third single conductive clip is connected to the negative
terminal of the cell being tested. These connections allow the
voltage drop across the cell being tested and the voltage drop from
one cell to the next cell to be taken. The voltage of the cell and
the voltage drop of the intercell connect are determined by
subtracting one measurement from a corresponding measurement.
Once connected, the user initiates the test sequence by first
reading and recording the cell float voltage. Once again the float
voltage is a no load voltage test reading which helps ascertain
whether the battery charger is set or sitting at the correct
voltage and determines whether a cell is suffering from a short
circuit. In the load test, which subsequently follows, the battery
tester automatically connects by keypad or keyboard commands a
fixed load resistance across the cell and the intercell being
tested forcing a current of approximately 70 AMPS to flow from the
battery through the load for a few seconds. During this load
condition, the instant invention reads the current and voltage
flowing through the intercell conductor and the current and voltage
across the internal cell to determine the intercell connection
resistance and the internal cell resistance, respectively. These
resistance measurements are easily obtained by dividing the voltage
readings by the current readings which are stored in and pulled
from RAM.
Data extraction and analysis is possible with the instant invention
wherein the battery tester is connectable to a PC compatible
computer. The instant invention provides subroutines for data
extraction wherein the test results are downloaded through a serial
port cable into the computer program. The test results may be
imported into the program of the instant invention and the data
analyzed and displayed in an easy to read bar graph or tabulated
format. In one alternative, the tabulated test results can be saved
in an ASCII or command, delineated format enabling the user to use
commercial, or off the shelf programs to generate customized
reports. In any event, once the float voltage and load voltage
readings are obtained from the test, the battery tester multimeter
may download the resistance reading and other data readings or
calculations to a standard personal computer through a serial port.
This is done by connecting the tester to a standard personal
computer via a conventional serial port, such as the RS-232. Once
the serial port connection is made, the instant invention provides
a downloaded menu driven program into a computer for further data
extraction, analysis and reporting. Thus the data may be further
analyzed and used to create easy to read graphs and printouts from
the personal computer. A computer however is not necessary for
obtaining the necessary readings, or determining the battery cell
integrity, or battery capacity. The instant invention generating
reports and displays standard analysis measurements, such as
internal cell resistance, intercell connection resistance, cell
float voltage, low load voltage, cell specific gravity and cell
temperatures, among other readings.
A summarized account of the instant invention features includes
float voltage readings, internal cell resistance measurements,
intercell resistance measurements, auto ranging, data extraction
and analysis, system display, and battery power. The float voltage
readings measures the voltage applied during full float operation
where no load is applied. The voltage range covers all cell or cell
modules up to 16 volts, and reading accuracy is within preferably
four full digits. The battery tester circuitry is designed for
handling and processing a limited voltage, such as four volts,
therefore the instant invention may incorporate a voltage divider
or input divider circuit for cutting down proportionately the input
voltages for data manipulation. As noted above, the internal cell
resistance is ascertained by measuring the cell's response to a
momentarily applied load across the cell. The instantaneous voltage
drop experienced by the applied load and load current drawn is used
to calculate the resistance. The battery test hardware and software
algorithm perform calculations to arrive at the measurement. The
instant invention also takes these measurements and uses it for
floating on line analysis. This helps to determine weak, and
potentially failing cells when comparing the internal cell
resistance of all the like cells in the string of cell modules. The
instant invention also measures and displays the total electrical
resistance of the intercell conductor connection between the
terminals of adjacent cells, or the intercell connection that are
connected to each other. This measurement includes the resistance
of the intercell connector and the contact resistance with the
posts or cell terminals. Since the instant invention is software
driven, the battery tester is able to automatically select the
correct voltage range and load resistor for the test being
performed. The instant invention may be able to do this by taking
preliminary voltage measurements of the cell or plurality of cell
modules being tested to select a voltage range. The battery tester
preferably provides four digits of accuracy for all
measurements.
Instructions and test results are provided on the battery tester
unit display or downloaded to a computer for computer display. The
display window of the instant invention preferably maintains a four
line by 20 character display. The instant invention may be powered
by a self contained, rechargeable battery built into the case of
the instant invention. The self contained rechargeable battery may
be recharged or the unit may be set up for AC power operation from
a wall plug transformer modular.
The instant invention provides a first set of probes and is
designed so that it may also be used as a volt meter or multimeter.
The battery tester also signals when probes are properly connected
across a cell's terminal post by showing the voltage reading on the
display and emitting an audible beep within two seconds. A display
indication that the reading has been stored in the unit's RAM
memory may also be done. When the two voltage probes are lifted for
measuring the next cell in the series, the instrument automatically
indexes the display and memory stack to the next higher number when
the voltage probes make contact with the next cell. The instant
invention and software employ conventional pointer indexing means
in the microcontroller and RAM registers. By automatically indexing
display and memory storage positions, the instant invention allows
a user to make valid recorded voltage readings at a rate of
preferably 10 to 12 per minute.
Specific gravity and temperature measurements may be made by the
instant invention and displayed. To measure specific gravity and
temperature of a cell or cells, the display via software may prompt
the user to key in the reading for each cell. The instant invention
automatically inserts the first two numbers of a specific gravity
reading to speed up the entry process. For example, for a 1215
reading the display may show SG equal to 12--and the user enters
15. These readings may be automated in the future but in the
meantime this process is still more efficient than the present pen
and paper approach. Thus, the invention merely allows for the
recording of the specific gravity and temperature within the
modular so that it may be used in future calculations and/or
downloaded into a PC compatible computer.
The preferred embodiment of the instant invention includes an A/D
converter, such as those conventionally known for converting
readings from analog to digital for calculating, processing and
storing in the permanent or temporary RAM locations. The A/D
converter employed by the instant invention effectively enables the
measurement of DC values while totally ignoring any AC signals
flowing through the battery at the same time or other signals which
may be attributed to noise. This is another way the instant
invention is capable of on line operation even in high noise
environments.
The instant invention may be used on any type of batteries and is
able to predict capacity reduction based on various battery
conditions such as corrosion, grid growth, sulfation, dry out,
manufacturing defects, various charge conditions and
temperatures.
In accordance with these and other objects which will become
apparent hereinafter, the instant invention will now be described
with particular reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a circuit representation of conventional batteries
illustrating the metallic resistance and electric mechanical
resistance of the battery cell and the capacitance.
FIG. 2 is a simple pictorial diagram of the battery tester of the
instant invention connected to the battery cell and module being
tested.
FIG. 3 is a block diagram of the preferred embodiment of the
battery tester of the instant invention illustrating the
interconnections between the hardware devices and the battery cells
being tested.
FIG. 4 is a block diagram of the preferred embodiment of the
instant invention illustrating the hardware in more detail and the
communication links between the integrated circuit chips of the
instant invention.
FIGS. 5a-5h is a detailed electrical schematic diagram of the
preferred embodiment of the instant invention.
FIG. 6 is a flow chart of the software algorithm of the preferred
embodiment of the instant invention illustrating the flow of basic
algorithm steps used in conducting tests on battery cells.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
With reference to the drawings, FIGS. 2-6 depict the preferred
embodiments of the battery tester system 10 which generally
comprises a data storing battery multimeter 10 for measuring,
recording and displaying readings of internal cell voltage,
internal cell resistance and intercell connection resistance. Other
data specific to each battery being tested may be manually entered
and stored in the battery tester 10, such as specific gravity and
temperature. The instant invention is an automated microprocessor
or microcontroller operated testing and display unit for processing
and displaying the foregoing measurements. The instant invention is
preferably computer compatible whereby it may be electrically
linked to a personal computer 230 or network for downloading or
extracting data recordings from the tester obtained by the tester
10 during testing for further analysis and report generation. The
battery tester 10 may be used for automatically testing a single
cell 5 or multicell battery source module. Large industrial type
backup DC battery sources typically include a plurality of battery
cells 5 electrically connected in series by intercell
connectors.
The preferred embodiment of the instant invention is a self
contained, battery powered unit 10 comprising a microcontroller 130
or microprocessor with internal or external RAM, ROM and a timer,
load resistance circuit 20, a display 110 and rechargeable battery
210. The tester 10 of the invention measures float voltages,
internal cell resistance, intercell resistance and load voltages
for at least one battery cell 5. Float voltage is a measurement of
battery voltage during full float operation wherein no load is
applied and the cell is charged. The internal cell resistance test
determines the internal resistance of a battery cell 5 by how that
cell responds to a momentary load 20-26. The instantaneous voltage
drop across the cell and load current are measured and used by the
battery tester 10 to calculate the cell's internal resistance. The
battery tester 10 provides microprocessing hardware and software
algorithms, such as that shown in FIG. 6, which make the
measurements possible on battery cells that are floating and that
have loads while they remain on line. That is, unlike the
background systems, the battery tester 10 performs DC load testing
while a battery cell or modular of cells are in service and while
the battery charger remains electrically connected and powered.
Intercell resistance is a measurement of the total electrical
resistance of the connection 7 electrically linking two battery
cells. This connection is usually a conductive link 7 from the
positive post of the cell being tested to the positive post of the
electrically linked or next cell. The intercell resistance test
checks for bad connections. This is important for finding
intermittent intercell connections, dangerous heat build up,
voltage drops occurring between cells (a problem which can cause a
loss of energy in critical testing or operating applications such
as in telephone systems where small voltage drops can result in
significant system failure), and dangerous conditions caused by
intermittent connections such as electrical fires.
The battery tester 10 may provide two sets of test leads, or two
sets of test leads connectable to the tester may be used with the
instant invention for making the foregoing measurements. One set,
or the first set, is a standard set of digital voltmeter probes,
while the second set 14 comprises a three clip set used in the
multimeter mode of the battery tester, as seen in FIG. 2. The three
clip set comprises two dual conductor test clips 14a, 14c and a
third single conductor clip 14b. In the two dual conductor test
clips a conductive element is situated in each leg of each clip so
two conductive paths are provided. One path in each of the two
clips allows a lead to be connected between the positive terminal
of two battery cells via inputs 56 and 58, while the second path
allows voltage measurements and/or current measurements to be made
via inputs 50 and 54. The two dual connector test clips are used
for connecting across the cell 5 being tested and its associated
intercell connector 7 making the electrical link from the positive
post of the cell being tested to the positive post of the adjacent
cell. The third single conductor clip defined by the second set is
used for connecting to the negative terminal of the cell being
tested for measuring voltage drop and/or voltage across the cell
being tested and the intercell connector via input 52. From these
connections the instant invention may be utilized for making the
foregoing measurements. Once connected, the user initiates the test
sequence. First, the battery tester 10 measures and records the
cell float voltage before the load is applied. Next, the battery
tester 10 applies or connects a fixed resistance load 21, 26, and
22 or 24 across the cell being tested and the intercell being
tested, forcing a current of approximately 70 amperes from the
battery to flow for a few seconds through the load. Preferably,
either a 2 volt, 6 volt or 12 volt load is applied. These leads are
selected by triggering automatically either relay 21a, 24a or 26a,
respectively. During this loaded condition, the battery tester 10
reads the current and voltage drawn which is necessary to calculate
the intercell connection resistance and the internal cell
resistance. When testing is completed, the user may connect the
battery tester 10 via a serial port 180, such as RS-232, into a
standard PC compatible computer and initiate the software
algorithms of the instant invention. The software imported is menu
driven for extracting data and making analysis and report profiles
as supplied by the instant invention. Once data is extracted from
the battery tester 10 the information may be displayed in an easy
to read format on the accompanying computer 230 being used.
However, the user may merely use the battery tester 10 as defined
to generate a report and analysis and use its display 110. In the
alternative, a user may download the software defined by the
instant invention into the PC for operating the instant invention.
However, it is preferred that the battery tester 10 be used for
conducting the load and no load voltage measurements and the
resistance calculations once the connections are made and then
subsequently transferring the data stored in the tester 10 to the
serial port linked computer.
The battery tester 10 provides the hardware and software algorithms
for conducting the above-noted measurements. Therefore, the instant
invention comprises ROM 140-150, RAM 160-170 and microprocessing
hardware. In the preferred embodiment, the instant invention
comprises a resistance loading device 21-26, load module driver
circuit 80, a parallel input/output controller (PIO) 92 and circuit
90, a microcontroller 130, program ROM 140, upload program ROM 150,
program RAM 160 which may include a temporary memory RAM, data
storage RAM 170, address decoder circuit 120 for interfacing and
communicating with the noted ROMs, RAMs, microcontroller 130, and
PIO 92, an input divider circuit 40 and pre-AMP circuit 30, a
multiplexer (MUX) 60, and an A/D converter circuit 70 system. The
instant invention may also include a display 110, keyboard 101 and
a keyboard decoder 100 which interfaces with the PIO 92. In
addition, the invention includes a backup power supply 200,
including a battery 200 and battery charger 210. In short, the
essential elements of the instant invention are the microcontroller
130, at least one ROM 150, at least one RAM 160, a PIO controller
92, an A/D converter 70, and an adjustable resistance load circuit
20 which may be interchangeably applied for different load
levels.
With reference to FIG. 2, a simple diagram illustrates the complete
unit of the instant invention 10 connected or linked by the three
clip set or second set 14 to a cell 5 being tested, the intercell
connectors, and the corresponding adjacent cell 6. As can be seen
with the second set, one clip 14a is connected to the positive post
5a of the cell being tested, the second clip 14b is connected to
the negative post of the cell being tested, and the third clip 14c
connected to the positive post of the corresponding cell 6. These
connections allow the battery test instrument 10 to test and read
float voltage, cell load voltage, current draw, intercell voltage
drop, and intercell and internal cell resistance as calculated from
the voltage drop and current draws. The current draw is really the
current drawn from the battery as caused by the load applied.
With reference to FIG. 4, a more detailed block diagram of the
hardware of the battery tester 10 is shown, illustrating the input
divider circuit 40, pre-AMP circuit 30, multiplexer 60, resistance
load circuit 20, load driver circuit 80, PIO 92, analog to digital
(A/D) converter 70, microcontroller 130, RAM 160-170, ROM 140-150,
the display 110, the keyboard decoder 100, the keyboard 101, the
RS-232 serial interface 180 and the power supply. The input divider
circuit 40, shown in FIG. 3, is electrically coupled in shunt
across the positive and negative terminals of the tested cell 5.
This coupling shunt actually occurs between the tested cell V1
input 54 and the V2 input 52 which correspond to the positive
terminal post and negative terminal post, respectively, of the
tested cell 5. The input divider circuit takes the voltage input
from the tested cell 5 and reduces it by voltage dividing circuitry
to a level below a predetermined threshold, e.g. for volts, so that
it may be received, read and processed by the A/D converter. The
input divider circuit 40 receives voltage inputs from cell 5 and
reduces them to the preferred DC voltage. The input divider circuit
40 is designed to receive up to 16 volts and reduces inputs to a
maximum voltage of 4 volts. These levels have been selected since
most batteries used today do not exceed 16 volts as higher voltage
requirements are obtained by connecting battery cells in series.
Therefore, the input divider circuit 40 may be designed for
receiving higher direct current voltage inputs without departing
from the scope and spirit of the instant invention. The pre-amp
circuit 30 comprises an amplifier circuit electrically shunted
across the intercell conductor link 7 for receiving, amplifying and
measuring the voltage drop across the intercell conductor 7. As
shown in the figure, the pre-amp 30 is connected to the V2 input 52
and the V3 input 50 which correspond to the negative terminal post
of the tested cell 5 and the positive terminal post of the series
connected cell 6, respectively. The pre-amp circuit 30 simply
amplifies the DC voltage drop input received from the drop across
the intercell since the drop is normally low and requires
amplification for accurate processing.
The multiplexer circuit 60 comprises a conventional MUX integrated
circuit chip which selects inputs in a predetermined order dictated
by the system's software and PIO controller for routing to the A/D
converter. The MUX 60 includes a plurality of solid state relays,
or similar relays, which are sequentially triggered as determined
by the software and PIO controller and outputted to the A/D
converter. The outputs from the pre-amp circuit 30 and the input
divider circuit 40 are fed into the MUX 60. In addition, the
current sense lines from the positive and negative load inputs 58,
56 respectively, as shown connected to the load resistor 26, are
also fed into the MUX 60. The A/D converter circuit 70 merely
converts analog inputs to digital outputs for processing by the
rest of the circuit components such as the PIO controller 92,
address decoder 120, the microcontroller 130 and the ROM and RAM
storage locations 140-170. The A/D converter circuit 70 includes an
A/D reference circuit 74 and an A/D clock 76. The A/D converter
circuit 70 comprises a conventional analog to digital converting
circuit which utilizes A/D reference inputs and A/D clocking for
referencing analog to digital conversion and timing.
The load circuit 20 provides a series of resistive loads including
preferably 2 volts, 6 volt and 12 volt loads for placement across
the V1 and V3 terminal post, i.e. the positive terminal post on the
tested cell 5 and the positive terminal post on the series
connected cell 6, via positive and negative load inputs 58 and 56,
respectively. These loads are placed across the positive terminal
post of the series cells for drawing current and taking current
sense measurements via current sense lines 28 and 29 electrically
tapping to load resistor 26 as shown in FIG. 3. These loads may be
user selected from the keyboard or keypad 101 or automatically
selected via the software and PIO controller 92. The loads in the
loading circuit 20 include a 2 volt relay 21a, a 6 volt relay 24a
and a 12 volt relay 26a which are electrically coupled to and
responsive to the load driver circuit 80. The load driver circuit
80 controls these relays 21a, 24a, and 26a while the load driver
circuit 80 is controlled by outputs from the PIO controller 92.
That is, the load driver circuit 80 and the PIO controller 92 are
electrically interfaced as are the load driver circuit and the
resistive load circuit 20.
The PIO controller 92 is also electrically coupled to the
multiplexer's circuit 60, for controlling the same. The PIO
controller 92 further receives outputs from the keyboard decoder
100 which receives its inputs from the keyboard or keypad 101. The
PIO controller 92 is also electrically interfaced with the
microcontroller 130, the A/D converter circuit 70 and the address
decoder circuit 120 via 16 byte and 8 byte address bus and data bus
links, respectively, 220, 222, for transferring control and data
signals. The PIO controller 92 is a programmed input and output
controller for controlling inputs and outputs from the A/D
converter 72, the keyboard decoder 100, the multiplexer 60, the
load driver circuit 80 and the ROM and RAM locations 140-170. The
PIO controller 92 may be a conventional program input and output
integrated circuit chip. The PIO controller 92 may be further
defined as a parallel input/output integrated circuit which
provides additional input and output lines for transmitting
non-communication busses capable of handling 8 byte to 32 byte
words such as those from the load driver circuit 80 which turns on
select relays.
The keyboard decoder 100 is electrically interfaced, preferably by
a multilink cable or bus to the keyboard or keypad 101 for
receiving and decoding input from the keyboard 101 for running
tests as dictated by the user. The keyboard or keypad is accessible
by any user from the outside of the unit enclosure casing as shown
in FIG. 2. The keyboard decoder produces outputs which electrically
interface with the PIO controller 92. Furthermore, the keyboard
decoder outputs are electrically connected to the microcontroller
at select pin connections on the keyboard decoder integrated
circuit chip and the microcontroller for processing user interface
inputs.
The microcontroller 130 of the instant invention, as shown in FIGS.
3 and 4 electrically interfaces and controls signal and data
processing to the program ROM 140, the upload program ROM 150, the
program RAM 160, the data storage RAM 170, the address decoder 120,
the display 110, the A/D converter 72 and the PIO controller 92
based on selected inputs from the keyboard decoder 100, the PIO
controller 92, the address decoder 120, the information serial port
180 and other inputs as shown in the detailed circuit diagram of
FIG. 5. The microcontroller may be described as a microprocessor
having internal RAM, ROM and timer circuitry which in most
conventional microprocessors is outside the integrated chip. The
microcontroller 130, as shown in the instant invention, interfaces
with the program and data ROM and RAM locations as shown. In the
alternative, a conventional microprocessor may be utilized for
accomplishing the same results. The microcontroller 130 also
interfaces with an address latch integrated circuit 125 which is
comprised in the address decoder 120 shown in FIG. 3 and FIG. 4.
Referring to FIG. 5, the address latch is shown electrically
interfaced to the microcontroller 130, the address decoder 120 and
the PIO controller 92 for addressing control and data signals
between these circuits and the ROM program memory 140, the upload
program ROM 150, the program RAM 160 having temporary scratch pad
memory and the data storage RAM 170. The address latch circuit 125
may interface with the microcontroller 130 via a 16 byte address
bus. Because the microcontroller 130 typically has limited lines,
the first 8 bytes of the address bus are also data bus latches
while the other 8 bytes are for the address and are tied to the
address bus. That is, that total bus size from the microcontroller
130 is 16 bytes which uses the 16 bytes as an address bus while the
first 8 bytes comprise a databus latching medium.
The address decoder 120, shown in FIGS. 3, 4, and 5 (i.e. the
decoder in FIG. 5) decodes the target address based on user and
hardware input thereby identifying and controlling the
communications with the microcontroller 130. The decoder 120,
determines which peripheral, such as a RAM, ROM, PIO, serial port
or display, the microcontroller 130 wants to talk to and decides
which peripheral communicates with the microcontroller 130 at a
given time. Accordingly, the decoder 120 interfaces with the RAM
and ROM locations, 140-170, and the display 110, as well as the
microcontroller 130. With reference to FIG. 5, the decoder also has
some electrical interconnection with the A/D converter 72 and the
PIO controller 92.
An interface serial port 180 is also shown in FIGS. 3 and 4 for
communicating with computer peripherals. The interface serial port
is preferably an RS-232 serial port interface but may be any other
conventional communication link for communicating with the
microcontroller without departing from the scope and spirit of the
instant invention. The serial port interface allows obtained data
measurements and calculations to be downloaded along with a menu
driven program into a peripheral computer so that battery cell data
may be further analyzed for determining battery cell integrity. A
list of menu options may also be downloaded to a computer over the
serial port so that the user may easily manipulate data inputs from
the battery tester 10 or extract other information from the battery
tester 10 and exercise various optional subroutines for extracting
and analyzing data procured from the battery tester.
The instant invention is preferably powered from a conventional
wall outlet supplying 110 to 120 VAC. In addition, the instant
invention supplies a backup rechargeable battery 205 source for
providing backup power to the battery tester unit 10 in the event
of main VAC power failure. A power supply charger 210 is supplied,
as shown in FIGS. 3 and 4, for charging the backup battery 205. The
power supply in FIG. 4 is shown by the reference numeral 200 which
includes the main and backup power.
With reference to FIG. 3, another block diagram of the instant
invention is shown, a simplified block diagram illustrating the
electrical links and communication between the display 110,
keyboard 101 and keyboard decoder 100, PIO controller 92, address
decoder 120, the resistance load circuit 20 including resistance
loads 21-26, load module driver circuit 80, input divider circuit
40, pre-AMP circuit 30, multiplexer 60, A/D converter circuit 70,
microcontroller 130, and the ROM 140-150 and RAM 160-170. The ROM
includes program ROM 140 and upload program ROM 150, while RAM
includes programmed RAM and temporary memory RAM 160, data storage
RAM 170. In FIG. 3 the detailed breakdown of ROM and RAM are not
shown wherein they are merely shown as ROM and RAM memory but
nonetheless accomplish the same results as discussed with reference
to FIG. 4. Also included is serial port 180, and the power supply
200 which includes conventional 110-120 VAC wall outlet power and a
power supply charger 210 for charging a backup battery 205. With
reference to FIG. 3 and 4, communication between the ROM and RAM
locations, the address decoder 120, which includes the address
latch 125 and decoder 126, the PIO controller output 92, the A/D
converter 72, and the display 110 are typically conducted over 8
and 16 byte address buses 222 and 220 respectively, as previously
discussed. The routing and controlling of measurements from the
current sense lines 28, 29 and voltage drop readings between 50, 52
and 54 are dictated by the MUX 60 which receives current sense and
voltage drop analog inputs and outputs those to the A/D converter.
The MUX 60 thereby selects inputs to the A/D converter 72 for
reading. The inputs selected include the intercell voltage drop,
the battery cell voltage drop and the current load as internally
measured. The A/D converter 72 converts the analog signals to
digital for routing to the microcontroller 130 and the ROM and RAM
locations 140-170.
As seen in FIGS. 5a-5h, a more detailed schematic diagram of the
instant invention hardware is shown. The various circuits and their
interface and interaction as noted above is shown in detailed
schematic view in FIG. 5. The address latch 125 and decoder 126,
comprising the address decoder 120, are shown interfacing over 8
byte and 16 byte buses with the PIO controller 92, the ROM program
memory 140, the ROM software update 150, the program RAM or
temporary scratch pad memory 160 and the data storage RAM 170 and
the microcontroller 130. The exact PIN locations are not identified
but the electrical communication is clear. Voltage inputs from the
tested cell 5 and the series connected cell are received by the
input jack J4 and voltage divided by the input divider circuit 40
which includes relays 42, 44, and 46. The intercell conductor
voltage drop across V2 and V3, i.e. 52 and 50, are amplified in the
pre-amp circuit 30 which includes amplifier 32, and variable
amplification resistor 33, relay 34, a varister 38 and signal
conditioning resistive loads 36 for dictating the level of
amplification. The load driver circuit 80 controls the 2 volt, 6
volt and 12 volt relays 21a, 24a, and 26a, respectively, via the
PIO, transistors 82, 84 and 86 and their corresponding resistive
loads. The transistor 88 shown in the load driver circuit 80 is
connected to an 8 volt battery supply as shown, while the
transistor 89 is electrically coupled to a fan control also shown.
The keyboard decoder integrated circuit 100 electrically interfaces
with the keyboard and keypad 101 and supplies outputs to the PIO
controller 92 and microcontroller 130. The PIO controller 92 is
selectably interfaced with the load driver circuit 40 as shown for
automatically selecting the appropriate loads for the tests being
conducted by the user as dictated through the user interface 101.
The PIO controller 92 communicates with the A/D converter 72 ROM
and RAM memory locations 140-170, the microcontroller 130 and the
decoder 126 as shown. The PIO controller 92 primarily communicates
over an 8 byte bus with the address latch 125 and the ROM and RAM
locations 140-170, and the microcontroller 130 as shown. The
microcontroller 130 establishes a communication link with the
serial port 180 as shown, wherein the serial port incorporated is
an RS-232 as shown. The RS-232 serial port 180 is coupled to a
multi-pin jack J1 as shown. An optional audible buzzer 131, as
shown, may be connected to the microcontroller 130 for sounding an
audible alarm when positive connections are made with the tested
cell 5. The buzzer is referenced by numeral 131. The A/D clock used
for controlling the timing of the A/D converter 72, as shown by
reference numeral 76, is preferably a counter divided by sixty for
clocking down. The A/D clock comprises NOR gates 76a and 76b, a
crystal oscillator 76e connected to integrated chip 76f which feeds
outputs to NOR gate 76b, and flip flops 76c and 76d which provide
outputs to the A/D converter 72 as shown. The A/D reference 74
provides reference voltages to the A/D converter 72 and comprises
an integrated chip 74a and a reference adjustment resistive load
74b, as shown. The power supply 200 is also shown in FIG. 5 and
includes a fuse 201, preferably rated for 1 to 2 amperes, and
voltage controller chips 202 and 203. Grounding capacitors are also
shown for filtering out noise and they are referenced by numeral
204 collectively. The foregoing generally outlines the schematic of
FIG. 5, but more detailed analysis may be made and referenced to
the schematic as shown.
A flow chart of the instant invention is shown in FIG. 6,
illustrating the main and basic steps conducted. This software
algorithm of the instant invention communicates and connects
conventional hardware components in a unique manner to provide
automatic testing of battery cells in a way undisclosed by
background devices. The flow chart of FIG. 6 is referenced by
numeral 300 where it begins at the starting point 310. The battery
cell to be tested 5 is first connected with the second set three
clip probe, as previously discussed. After the connections are made
to the battery cell being tested 5 and the series connected cell,
as shown in FIGS. 3-5, the software of the instant invention reads
and stores float voltages, that is the battery cell voltages before
a load is applied. See block 312. Subsequently, as shown in block
314, the instant invention applies a resistive load or loads to the
tested cell 5 via the load driver circuit 40. Before proceeding,
the instant invention preferably verifies proper and safe
connections and conditions by reading the current draw to verify
whether it is within proper limits. If this test fails then the
testing is terminated as indicated by block 318. If the current
readings are within the predetermined limits then the test proceeds
as shown by decision block 316. A load preferably remains
electrically coupled to the tested cell and intercell connect 7 for
a minimum of 4 seconds thereby allowing for natural voltage drop in
the battery which occurs instantaneously as discussed and noted
above. After this predetermined time lapse as shown by block 320,
the instant invention subroutines cause the current draw and
intercell voltage to be read or measured for calculating the
intercell resistance. Block 322 further shows that after reading
the intercell current and voltage drop, calculations are made by
the algorithm to determine intercell resistance which is
subsequently stored in the data storage RAM location 170. Once
again, the intercell resistance is a resistance measurement and
calculation of the intercell connect 7 joining the tested cell and
series cell in an electrical series and is thereby a calculation of
the intercell connect voltage drop divided by its current draw. The
current sense lines 28 and 29 allow for the reading of currents.
The internal cell resistance is next determined for the cell being
tested 5 by reading the internal cell voltage underload and the
current draw. Subsequent to taking an internal cell voltage reading
under load, the load is automatically removed and the internal cell
voltage is once again measured. See blocks 324 and 326. To
determine the internal cell resistance the calculation is made
whereby the internal cell voltage with no load is subtracted from
the internal cell voltage underload and then divided by the current
measured. This internal cell resistance calculation is then stored
in the data stored RAM location 170. This subroutine as illustrated
in FIG. 6 just shows the basic steps and outlines of a typical
measurements and calculations for determining voltage drops,
current readings and intercell and internal cell resistance. The
steps are used for arriving at the measurements and calculations
for voltage, current and resistance, and may vary without departing
from the scope or spirit of the instant invention. That is, the
instant invention provides an automated way of applying and
removing loads and performing integrity tests on battery cells for
determining a battery cell's capacity. The tests performed are
controlled by software which performs DC load testing in an
automated way and stores the results in RAM and temporary RAM
memory locations for performing calculations and extracting the
data obtained. The data extractions may be imported to a network or
computer peripheral over the serial ports, as shown and discussed
with reference to the figures. The instant invention also supplies
a first set of probes for conducting conventional voltmeter and
multimeter readings apart from the automated test as just
discussed.
The instant invention has been shown and described herein in what
is considered to be the most practical and preferred embodiment. It
is recognized, however, that departures may be made therefrom
within the scope of the invention and that obvious modifications
will occur to a person skilled in the art.
* * * * *